Department of Applied Materials and Optoelectronics Engineering, National Chi-Nan University, No. 1, University Road, Puli, Nantou County 54561, Taiwan.
Opt Lett. 2011 Jun 1;36(11):2008-10. doi: 10.1364/OL.36.002008.
We present a modified end-fire coupling method to reconstruct two-dimensional index profiles of optical waveguides. The reconstruction is based on the measured differential optical fields and an inverse algorithm for the Helmholtz equation. The differential fields are obtained from spatially perturbed images recorded by a CCD camera. A closed-loop piezoelectric stage given a sinusoidal wave and an oil-immersion objective lens for high-resolution images are used in the measurement. A single-mode fiber and a Ti:LiNbO(3) waveguide with known index profile at 632.8 nm are measured for demonstration. The measured index profiles agree quite well with core regions of known index profiles.
我们提出了一种改进的端射耦合方法来重建二维光波导的折射率分布。重建是基于测量的微分光场和亥姆霍兹方程的逆算法。微分光场是由 CCD 相机记录的空间扰动图像得到的。在测量中使用了一个带有正弦波的闭环压电台和一个用于高分辨率图像的油浸物镜。我们用单模光纤和 Ti:LiNbO(3)波导进行了测量，这两种波导在 632.8nm 处的折射率分布已知。测量得到的折射率分布与已知的芯区折射率分布非常吻合。
